The name Pangaea is derived from Ancient Greekpan (πᾶν) meaning "entire," and Gaia (Γαῖα) meaning "Earth." The name was coined during a 1927 symposium discussing Alfred Wegener's theory of continental drift. In his book The Origin of Continents and Oceans (Die Entstehung der Kontinente und Ozeane), first published in 1915, he postulated that all the continents had at one time formed a single supercontinent which he called the "Urkontinent", before later breaking up and drifting to their present locations.[4]